Background
The nitrogen pollution in the water body is more and more serious, and the frequent occurrence of eutrophication causes the high attention of people. How to efficiently and economically remove nitrogen-containing compounds in water becomes a popular problem for the study of scholars. Among them, the anammox process is favored by most scholars because of its excellent energy saving effect.
The anaerobic ammonia oxidation process is a novel biological denitrification process which can simultaneously convert ammonia nitrogen and nitrite nitrogen into nitrogen by utilizing Anammox bacteria. Successful start-up and operation of the anammox process requires the consumption of large amounts of nitrite. How to obtain nitrite continuously and stably is still a difficult problem which is difficult to solve, and the problem of nitrite sources is solved by two processes of short-cut nitrification and short-cut denitrification in the existing engineering test. Because the short-cut nitrification applied to domestic sewage at present is difficult to maintain for a long time, and the influent water is often accompanied with that organic matters are not fully utilized to inhibit the subsequent anaerobic ammonia oxidation, the short-cut denitrification provides nitrite nitrogen for the anaerobic ammonia oxidation to be a good choice.
The short-cut denitrification process controls the denitrification process in the stage of generating the nitrite, namely, the denitrifying bacteria are prevented from utilizing the carbon source to further reduce the nitrite into nitrogen. Compared with short-cut nitrification, the short-cut denitrification has the advantages of effectively treating nitrate wastewater, fully utilizing organic matters in raw water and the like, and can realize synchronous removal of the nitrate wastewater and domestic sewage. However, the current research shows that the enrichment of the short-range denitrifying bacteria is difficult, the selectivity to carbon sources is strong, easily degradable organic matters are easily utilized, and the difficultly degradable organic matters are difficult to utilize.
Domestic sewage in China generally has the characteristics of low carbon-nitrogen ratio and mostly refractory organic matters, and the shortage of available carbon sources in the domestic sewage results in low short-range denitrification efficiency and high total nitrogen in effluent, so that the short-range denitrification efficiency is difficult to reach the first-level A standard, and the operation cost is increased by adding a simple carbon source for deep denitrification. Therefore, how to more effectively utilize organic matters in the domestic sewage as a carbon source to realize the short-cut denitrification is a problem worthy of research.
In recent years, researchers have found that redox mediators can greatly accelerate the activity of anaerobic microorganisms. Redox mediators are compounds that accelerate the transfer of electrons from the initial electron donor to the final electron acceptor, and can increase the redox reaction rate by one to several orders of magnitude. The related documents report that anthraquinone, as a redox mediator, can improve the activity of nitrate reductase and the activity of nitrite reductase, and has better promotion effect on key enzyme of nitrate reductase. The research shows that the concentration of anthraquinone in 25-75 μmol/L has the promotion effect on the accumulation of nitrite.
The method for starting the short-range denitrification by using the organic matters in the domestic sewage as the carbon source by adding the anthraquinone has the advantages of no need of an additional carbon source, realization of continuous and stable nitrite source and the like, and achieves the aim of synchronously removing the nitrate wastewater and the domestic sewage.
Disclosure of Invention
Compared with the traditional nitrification/denitrification process, the short-cut denitrification-anaerobic ammonia oxidation technology saves the aeration amount and the carbon source, and is a resource-saving and environment-friendly denitrification process. The invention provides a method for starting short-cut denitrification by taking organic matters in domestic sewage as a carbon source by adding anthraquinone, which can fully utilize the organic matters in the domestic sewage, does not need an additional carbon source, saves the cost and can stably obtain nitrite. The method can provide reference for engineering application of short-range denitrification-anaerobic ammonia oxidation.
A device for starting short-cut denitrification by adding anthraquinone and taking organic matters in domestic sewage as a carbon source is characterized by comprising a nitrate wastewater inlet tank (1), a domestic sewage inlet tank (2), a short-cut denitrification reactor (3), a water outlet tank (4) and an automatic control platform (5); the nitrate wastewater inlet tank (1) is connected with the short-cut denitrification reactor (3) through a first inlet pump (3-1); the domestic sewage inlet tank (2) is connected with the short-cut denitrification reactor (3) through a second inlet pump (3-2); the electric valve (3-3) for draining the short-cut denitrification reactor (3) is connected with the water outlet tank (4).
The short-cut denitrification reactor (3) is internally provided with a drainage electric valve (3-3), a stirring device (3-4), a DO on-line monitor (3-5) and a mud valve (3-6).
The first water inlet pump (3-1), the second water inlet pump (3-2), the electric drainage valve (3-3), the stirrer (3-4) and the DO online monitor (3-5) are connected with the automatic control platform (5).
The device and the method for starting the short-cut denitrification by adding anthraquinone and taking organic matters in domestic sewage as a carbon source are characterized by comprising the following steps: the periodic operation comprises the following steps:
1) and (3) starting a system: inoculating sludge rich in denitrifying bacteria in a short-cut denitrification reactor; the sludge concentration of the reactor after inoculation is controlled to be 2000-8000mg/L
2) Determining the input of acid salt wastewater and domestic sewage: organic matters in the domestic sewage are used as an organic carbon source, and the nitrate wastewater and the domestic sewage are pumped into the short-range denitrification reactor according to a certain proper carbon-nitrogen ratio. Determining the input amount of the nitrate wastewater and the domestic sewage according to the calculation formulas (1) and (2):
V1+V2=V*ρ(2)
note: COD-organic matter content in domestic sewage;
-nitrate concentration in nitrate solution;
V1-domestic sewage intake;
V2-intake of nitrate solution;
v-effective volume of reactor;
rho-drainage ratio;
C/N-ratio of organic matter to nitrate in the water inlet tank, and the set value is selected within the range of 3-6;
3) the runtime adjustment operation is as follows:
pumping the nitrate wastewater inlet tank (1) into the short-cut denitrification reactor (3) through a first inlet pump (3-1) before each period begins; the domestic sewage inlet tank (2) is pumped into the short-cut denitrification reactor (3) through a second inlet pump (3-2); then, an anthraquinone reagent is added into the short-range denitrification reactor (3) to ensure that the concentration of anthraquinone in the reactor is 25-75 mu mol/L, anoxic stirring is started, stirring is stopped until the concentration of nitrate nitrogen is less than 3mg/L or the accumulation rate of nitrite is more than 75%, precipitation and drainage are started, and the next period is started after the reactor is idle.
The invention relates to a device and a method for starting short-cut denitrification by taking organic matters in domestic sewage as a carbon source by adding anthraquinone. The invention has the following advantages:
1) anthraquinone is added to start a short-cut denitrification process taking organic matters in the domestic sewage as a carbon source, so that the organic carbon source in the domestic sewage is fully utilized, deep denitrification is realized, an external carbon source is not required, and the energy consumption of sewage treatment is reduced;
2) the production of nitrite in the nitrate reduction process can be stably and continuously realized, and an electron acceptor is provided for the subsequent anaerobic ammonia oxidation process;
3) organic matters in the domestic sewage are used for short-range denitrification, so that the inhibition of the organic matters on anaerobic ammoxidation can be avoided, and the stability of the subsequent anaerobic ammoxidation process is facilitated.
Detailed Description
The invention is further illustrated by the following figures and examples: as shown in fig. 1: a device and a method for starting short-cut denitrification by adding anthraquinone and taking organic matters in domestic sewage as a carbon source are characterized by comprising a nitrate wastewater inlet tank (1), a domestic sewage inlet tank (2), a short-cut denitrification reactor (3), a water outlet tank (4) and an automatic control platform (5); the nitrate wastewater inlet tank (1) is connected with the short-cut denitrification reactor (3) through a first inlet pump (3-1); the domestic sewage inlet tank (2) is connected with the short-cut denitrification reactor (3) through a second inlet pump (3-2); the electric valve (3-3) for draining the short-cut denitrification reactor (3) is connected with the water outlet tank (4).
The short-cut denitrification reactor (3) is internally provided with a drainage electric valve (3-3), a stirring device (3-4), a DO on-line monitor (3-5) and a mud valve (3-6).
The first water inlet pump (3-1), the second water inlet pump (3-2), the electric drainage valve (3-3), the stirrer (3-4) and the DO online monitor (3-5) are connected with the automatic control platform (5).
In the experimental process, the specific experimental water is taken from domestic sewage of family district of Beijing university of industry and effluent of a nitration reactor, and the specific water quality is as follows: COD concentration is 70-200mg/L, NH4 +-N concentration of 0-2mg/L, NO2 -Concentration of-N<1mg/L,NO3 -the-N is 10-30mg/L, and the pH value is 7.3-7.6. The experimental system is shown in figure 1, the reactor is made of organic glass, and the effective volume of the short-range denitrification reactor (2) is 10L.
The specific operation is as follows:
1) and (3) starting a system: inoculating sludge rich in denitrifying bacteria in a short-cut denitrification reactor; the sludge concentration of the reactor after inoculation is controlled to be 2000-8000mg/L
2) Determining the input of acid salt wastewater and domestic sewage: organic matters in the domestic sewage are used as an organic carbon source, and the nitrate wastewater and the domestic sewage are pumped into the short-range denitrification reactor according to a certain proper carbon-nitrogen ratio. Determining the input amount of the nitrate wastewater and the domestic sewage according to the calculation formulas (1) and (2):
V1+V2=V*ρ(2)
note: COD-organic matter content in domestic sewage;
-nitrate concentration in nitrate solution;
V1-domestic sewage intake;
V2-intake of nitrate solution;
v-effective volume of reactor;
rho-drainage ratio;
C/N-ratio of organic matter to nitrate in the water inlet tank, and the set value is selected within the range of 3-6;
3) the runtime adjustment operation is as follows:
pumping the nitrate wastewater inlet tank (1) into the short-cut denitrification reactor (3) through a first inlet pump (3-1) before each period begins; the domestic sewage inlet tank (2) is pumped into the short-cut denitrification reactor (3) through a second inlet pump (3-2); then, an anthraquinone reagent is added into the short-range denitrification reactor (3) to ensure that the concentration of anthraquinone in the reactor is 25-75 mu mol/L, anoxic stirring is started, stirring is stopped until the concentration of nitrate nitrogen is less than 3mg/L or the accumulation rate of nitrite is more than 75%, precipitation and drainage are started, and the next period is started after the reactor is idle.
Average COD, NH of the effluent during the run of the experiment4 +-N,NO3 --N,NO2 -The N, TN concentrations are respectively as follows: 37.04mg/L, 1.02mg/L, 7.28mg/L, 0.68mg/L and 8.56mg/L, and the water outlet indexes are stable and all reach the national first-class A standard.